Apparatus and method for moving a ferromagnetic element

Abstract

A device and technique for placing and moving a ferromagnetic element in an annulus between coaxially arranged cylindrical tubes. The device includes an electromagnetic ram moved along the interior of a cylindrical tube. The movable ferromagnetic element is magnetically coupled to the electromagnetic ram and moved by magnetic force to a location in the annulus defined by the tubes and magnetically coupled to the electromagnetic ram for movement in and removal from the annulus.

1. Apparatus for placing and moving a spacer ( 300 ) into and along an annulus ( 150 ) defined by inner and outer coaxial cylindrical tubes ( 100 ,  200 ), said apparatus comprising:
 a first push rod ( 1000 ); 
 a radially expandable generally toroidal pusher ( 600 ) surrounding and located at a first axial position on said push rod ( 1000 ); 
 a collet and mandrel ( 700 ) operatively associated with the push rod ( 1000 ) axially adjacent the pusher ( 600 ) for engaging an end of said inner cylindrical tube ( 100 ) and providing a generally frusto-conical surface from the outer diameter of the push rod ( 1000 ) to the outer diameter of the inner cylindrical tube ( 100 ); 
 a second push rod ( 1006 ) supported for axial movement by said push rod ( 100 ); 
 a magnetic ram operatively associated with the second push rod ( 1006 ) for movement therewith from a first position located radially inwardly of the pusher ( 600 ) to a second position located within the inner cylindrical tube ( 100 ) for creating a magnetic coupling with the pusher ( 600 ) and moving the pusher from said first location on the push rod ( 1000 ) into the annulus ( 150 ); and 
 wherein the pusher ( 600 ) comprises a plurality of arcuate ferromagnetic segments ( 601 ,  603 ) forming a generally toroidal, radially expandable ferromagnetic ring surrounding the push rod ( 1000 ) and normally located axially adjacent the fixed end ( 708 ) of the collet and mandrel ( 700 ) movable under the influence of a magnetic field from the electromagnetic coil ( 500 ) along the collet and mandrel ( 700 ) toward a radial shoulder ( 706 ) on a collet and mandrel finger ( 702 ) and into the annulus ( 150 ) between the inner and outer cylindrical tubes ( 100 ,  200 ) and thereafter movable under the influence of a magnetic field from the electromagnetic coil ( 500 ) to position a toroidal spacer ( 600 ) in said annular space. 
 
   
   
     2. Apparatus as defined in  claim 1  further comprising:
 a source of electrical current ( 1200 ); 
 an electric actuator and drive ( 1050 ) electrically connected to the source of electric current ( 1200 ); 
 said magnetic ram ( 400 ) including a coil ( 500 ) electrically connected to the source of current ( 1200 ) for generating a magnetic field; and 
 controls for switching and regulating the flow of electric current ( 1200 ) associated with the source of electrical current ( 1200 ) and electrically connected to the electric actuator and drive ( 1050 ) and the coil ( 500 ). 
 
   
   
     3. Apparatus as defined in  claim 2  further comprising:
 an axially movable, radially expandable collet ( 350 ) mounted on the push rod ( 1000 ) and normally located radially inwardly of the collet and mandrel ( 700 ) for expanding the collet and mandrel ( 700 ) into engagement with the inner cylindrical tube ( 100 ).